I recently changed all of the discs and pads on my V70 using Mintex replacements and haven't had a single squeal since. The Mintex pads come with an anti-squeal material moulded onto the back. Prior to the change, the brakes were getting very squeally - and were also worn. The noisiest was the driver's side rear and these pads were also the most worn of the lot (incidentally, the old pads also had anti-squeal material on them). Based on that, it would seem that excessive brake squeal probably indicates wear, so if your brakes are noisy it's probably time to get them changed.